Microlighters

Is it neccessary to have Egt in the 912? If so can someone explane why.
Cheers,Vernon.

Hi vernon11,

The cooling system of the 912 is primary liquid with radiators cooling both water and oil of the engine (seperate). Normally you would only have a water temp guage, which would monitor the temperature of the water and thus the temp at which the engine is running.

EGT and CHT is the only methods in which you can measure the temperature at which the 503 air cooled engine is running, because no water/coolant can be monitored.

If you really want to, I figure that you can install a EGT guage on a 912, but it would really be meaningless to you while you have your water temp guage running.

Regards.

THE EGT SHOWS YOU HOW LEAN/RICH YOUR ENGINE IS RUNNING.THE BING CARB ON 912 HAS THE ALT COMP BUT YOU STILL CAN CHANGE JETS AND SHIFT THE NEEDLE UP OR DOWN BMO THE CIRCLIP.THESE CHANGES WOULD GIVE DIFFERENT READINGS ON THE EGT

Thanks. I did not think there was any reall use for it. Have found one probe is faulty, and also the guage, so it is not worth replacing it.

Vernon.

Monitoring the EGTs is a very usefull tool.
On the 912/914 it is good to have one on each side, this will indicate how well synchronised your carbs are as well as the rich/lean state.
The actual numbers displayed are relatively unimportant, It is the trend you want to watch for any significant change.

The EGT measures your combustion temperature i.e. the temp at which the fuel is being burnt in the combustion chamber. It is a useful gauge to have in the case of mixture control when climbing or descending. It will also indicate whether you have a air/fuel related problem say if one of the carb rubbers gets torn. Due to the increase in the amount of air being sucked into the combustion chamber the EGT will show a rise in temp. ( Sucked in is the wrong term. It get's forced in due to a pressure difference but you know what i mean). You may get the situation where your coolant temp is ok but due to the torn carb rubber you end up with a hole through the piston. IMHO they are better to have than not to have.

thanks Ranger. That makes sence. I will reconsider.
Vernon.

I replaced one EGT Prope on my Rotax,
now the new Prope's reading is higher
than the old Prope, is this normal due to
the carbon on the old Probe or not ?

Regards
Willie

It is always good to replace both as their accuracy vary from batch to batch when they are manufactured but they are still within the specified tollerance.

hi willie, i had the same problem - only replaced one probe. check the lenght of the probes - they should be equal otherwise a different reading. the new probe i installed was 2mm longer than old probe so i used a washer to 'shorten' it / space it. that was the answer i got from rainier at mgl. problem fixed.